1. Field of the Invention
This invention relates to an improved process and catalyst for the production of methane-rich gas. More specifically, the present invention relates to the production of a product gas stream comprising at least 25 vol. % methane (dry basis) by reacting a feed gas stream, such as that produced by the partial oxidation of a liquid hydrocarbonaceous or solid carbonaceous fuel, in a reactor containing the improved catalyst. The product gas may be burned as a fuel without polluting the environment.
2. Description of the Prior Art
Synthesis gas containing methane may be made by the partial oxidation of a hydrocarbonaceous fuel using comparatively high steam to fuel weight ratios and no subsequent catalytic methanation step, as described in coassigned U.S. Pat. No. 3,688,438. In coassigned U.S. Pat. No. 3,890,113, a gaseous stream comprising H.sub.2 O and CO is produced by the partial oxidation of a hydrocarbonaceous fuel and is subjected to the water-gas shift reaction to produce a gaseous stream rich in H.sub.2 and CO.sub.2. This gas mixture is then subjected to conventional catalytic methanation after the mole ratio H.sub.2 /CO.sub.2 is adjusted to about 4 to 10. In coassigned U.S. Pat. No. 3,888,043, a large amount of nitrogen diluent is contained in the effluent gas stream from the partial oxidation generator. During the two conventional methanation steps with an intervening water-gas shift conversion step, the large amount of nitrogen diluent in the reacting gas stream helps to control the normally vigorous exothermic reactions which are going on.
In U.S. Pat. No. 4,032,556, the methane content of a gas produced by the hydrogenation of a liquid hydrocarbon with a hydrogenating gas at high temperatures is increased by contacting the gas stream with a supported nickel-urania hydrogenation catalyst comprising a maximum of 10 wt. % uranium. U.S. Pat. No. 3,993,459 pertains to a catalyst for converting higher hydrocarbons into gas mixtures containing carbon monoxide, methane and/or hydrogen in which the active components are oxides of the metals lanthanum, cobalt, nickel, uranium, cerium and thorium on an oxide substrate. The catalyst comprises from about 0.1 to 8 percent by weight of uranium. In U.S. Pat. No. 3,847,836 liquid hydrocarbons e.g. naphtha are steam reformed using a catalyst comprising nickel, and/or nickel oxide, together with a relatively smaller amount of uranium oxide supported on a carrier.